PERFORMANCE AND NUTRITIVE QUALITY OF DWARF AND SEMIDWARF ELEPHANTGRASS GENOTYPES IN THE SOUTH-EASTERN USA

Since the release of 'Mott' dwarf elephantgrass (Pennisetum purpureum) there has been renewed interest in using this grass species in cattle production systems in the south-eastern United States. The objective of this study was to evaluate 4 new dwarf or semi-dwarf elephantgrass genotypes for dry matter (DM) production, nutritive quality [crude pro tein (CP) and digestibility], plant morphology and persistence at 2 si tes in the south-eastern USA. The experimental genotypes, N114, N127, N128, and N129 plus cvv. Mott and Merkeron (a tall type) were establis hed using rooted cuttings in 1988 at Brooksville, Florida, and Tifton, Georgia. Total DM yield of the genotypes was similar across locations and years (1988-1990). Merkeron consistently produced at least twice as much DM at any given harvest date and total for the year (>25 t/ha) as any of the dwarf or semi-dwarf genotypes (5-15 t/ha). Dry matter y ields of N114 and N129 were better than or equal (P less than or equal to 0.05) to that of Mott (9-10 t/ha); only N127 averaged less DM prod uction. Although leaf:stem ratio (2-13.9) was negatively correlated wi th DM yield (r = - 0.23, P < 0.001), nutritive quality did not differ (P > 0.05) with genotype. Average CP (85-121 g/kg) and digestibility ( 547-717 g/kg) varied (P < 0.05) with harvest date, being highest at th e first harvest date (June) each year. It appears possible to select g enotypes such as N129 that have the high forage quality characteristic of Mott with increased DM production potential.